This invention is directed to a digital display electronic wristwatch utilizing a quartz crystal time standard capable of vibrating in the MHz range and in particular to the use of the thickness-shear quartz crystal vibrator having a frequency of vibration of at least one MHz as a time standard in a digital display electronic wristwatch.
The development of digital display technology has paralleled the rapid advance in small-sized electronic wristwatches of extremely high accuracy. When combined, such digital display electronic wristwatches have been able to provide numerous functions heretofore unavailable in electro-mechanical wristwatches. For example, the use of digital displays in electronic wristwatches has enabled same to be utilized as stopwatches for measuring periods of elapsed time to a one-hundredth and one-thousandth of a second degree of accuracy. Clearly, such degrees of accuracy would not be obtainable with a mechanical display electronic timepiece. Also, digital displays have permitted the display of temperature information, humidity information and basal body temperature.
Chronographic wristwatches having stopwatch capabilities have been rapidly developed to take advantage of the high accuracy afforded by quartz crystal time standards. Nevertheless, the accuracy of such electronic timepieces has been less than completely satisfactory, due in large measure to the inability to effectively and accurately adjust the timing rate grade, i.e., the frequency of the low frequency timing signals produced by the divider in response to the high frequency time standard signal applied to the divider.